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The results of a computer simulation examining the compliance of a given transcranial magnetic stimulation device to the 2010 International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines are presented. The objective was to update the safe distance estimates with the most current safety guidelines, as well as comparing these to values reported in previous publications. The 3D data generated was compared against results available in the literature, regarding the MCB-70 coil by Medtronic. Regarding occupational exposure, safe distances of 1.46 m and 0.96 m are derived from the simulation according to the 2003 and 2010 ICNIRP guidelines, respectively. These values are then compared to safe distances previously reported in other studies.

Resumo Os processos de soldagem Eletrodo Revestido e TIG, amplamente utilizados na indústria, são executados em grande parte de forma manual e neles são empregados níveis elevados de corrente afim de garantir maior produtividade. O emprego de correntes de alta intensidade conduz a geração de altos campos magnéticos, os quais de acordo com diretrizes relacionadas a saúde e segurança do trabalhador podem acarretar em efeitos nocivos à saúde humana. Assim, foram realizadas avaliações acerca da emissão de campos magnéticos em processos de soldagem Eletrodo Revestido e TIG em função das variáveis operacionais inerentes a estes processos e o nível de exposição de soldadores através da comparação com os limites de segurança estabelecidos pelas diretrizes mais atuais do ICNIRP. Os resultados mostraram que o campo magnético é maior a medida em que aumenta a corrente de soldagem e menor quanto maior for a altura do arco. O revestimento do eletrodo e o gás de proteção também influenciam na intensidade do campo magnético por interferirem, respectivamente, na estabilidade e no formato do arco elétrico. Os resultados mostraram ainda que o campo magnético é influenciado pela permeabilidade magnética do material de base. Abstract Welded Coated and TIG welding processes, widely used in industry, are executed largely manually and in them are used high levels of current in order to ensure higher productivity. The use of high intensity currents leads to the generation of high magnetic fields, which according to guidelines related to the health and safety of the worker can have harmful effects on human health. Thus, evaluations were made on the emission of magnetic fields in Welded Coated and TIG welding processes in function of the operational variables inherent to these processes and the level of exposure of welders by comparison with the safety limits established by the most current ICNIRP guidelines. The results showed that the magnetic field is larger as the welding current increases and the smaller the arc height. The electrode coating and shielding gas also influence the magnetic field strength by interfering, respectively, in the stability and shape of the electric arc. The results also showed that the magnetic field is influenced by the magnetic permeability of the base material.

Exposures to mechanical vibration at the workplace may occur from either hand-held powered tools (hand-transmitted vibration, HTV) or machines and vehicles driven in industry, forestry, agriculture or public utilities (whole-body vibration, WBV). Excessive exposures to HTV from powered processes or tools are associated with an increased occurrence of symptoms and signs of disorders in the vascular, neurological and musculoskeletal systems of the upper limbs. The complex of these disorders is called hand-arm vibration syndrome. Long-term occupational exposure to WBV is associated with an increased risk for disorders of the lumbar spine and the connected nervous system. With a lower probability, the neck-shoulder, the gastrointestinal system, the female reproductive organs, the peripheral veins, and the cochleo-vestibular system are also assumed to be affected by WBV. However, there is a weak epidemiological support for WBV-induced disorders of organ systems other than the lower back. In addition to the health effects of human vibration, this chapter reviews the currently available knowledge of the exposure-response relationships for HTV and WBV. Elements of prevention and health surveillance of vibration exposed workers are also provided.

Desarrollo de una metodología de base científica para la verificación y/o adaptación al cumplimiento de la nueva directiva comunitaria 2013/35/UE sobre exposición de trabajadores a campos de naturaleza electromagnética Escuela Técnica Superior de Ingeniería de Telecomunicación Universidad Politécnica de Cartagena

Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2019-03-21T17:29:23Z No. of bitstreams: 1 CLÁUDIO PEREIRA DA COSTA - DISSERTAÇÃO PPGEE 2011..pdf: 2548295 bytes, checksum: 4938124ffb155e52e05133fa620aeedb (MD5) Made available in DSpace on 2019-03-21T17:29:23Z (GMT). No. of bitstreams: 1 CLÁUDIO PEREIRA DA COSTA - DISSERTAÇÃO PPGEE 2011..pdf: 2548295 bytes, checksum: 4938124ffb155e52e05133fa620aeedb (MD5) Previous issue date: 2011-03 Neste trabalho é realizada a análise da exposição eletromagnética passiva à multifontes distribuídas em ambientes abertos. Para a devida caracterização do fenômeno estudado é descrita uma revisão bibliográfica dos principais conceitos e parâmetros eletromagnéticos presentes, além das principais normas e recomendações vigentes relacionadas à exposição eletromagnética, como também da técnica de otimização utilizada, algoritmos genéticos. São apresentados os resultados calculados de campos eletromagnéticos, com a presença de um modelo da cabeça humana, e as disposições dos arranjos obtidos em duas configurações: na primeira são apresentadas situações em que as antenas dipolo se encontram em posições prédeterminadas, as quais servem de base para a delimitação da região de estudo e análise dos níveis de campos eletromagnéticos calculados nessas situações. Posteriormente, o posicionamento das antenas é otimizado em algoritmo genético com o objetivo de obter e analisar o pior caso na região de estudo, os níveis de máximos de campos eletromagnéticos no usuário e na sua vizinhança, os quais são produzidos pela disposição do arranjo. Finalmente, os níveis de campos eletromagnéticos calculados foram comparados com os níveis de referência da norma, levando-se em consideração a potência, a posição espacial e a quantidade das fontes no arranjo. Também foram feitas algumas observações sobre os níveis de campos eletromagnéticos obtidos na presença de um modelo da cabeça humana. Por fim, são apresentadas as considerações finais e a possibilidade de trabalhos futuros sobre o tema. In this work it is presented an analysis of the passive electromagnetic exposure produced by distributed multisource in outdoor. In order to obtain an accurate characterization of the phenomenon it has been made a literature review of the basics concepts and electromagnetic parameters taking into account the existing standards recommendations related to electromagnetic field. It is also reported the optimization technique by genetic algorithms. It is presented the electromagnetic field calculated results with the presence of a human head model and the dispositions of the obtained arrays in two steps. In the first step, are analyzed situations in which the antennas are placed at predetermined positions according to the electromagnetic field levels calculated from the distributions of the antennas. Subsequently, the positioning of the antennas is optimized with genetic algorithm in order to obtain and analyze the worst case in the study area, the maximum levels of electromagnetic fields on the user and its vicinity which are produced by the provision of the arrangement. Finally, levels of electromagnetic fields were calculated compared with levels of reference ones reported by the standard is made taking into account the level of the power sources, its spatial position and their quantity in the array. It is also made some observations on the levels obtained in the presence of a model of a human head. Finally, we present the final considerations aiming at the possibility of future works on the subject.

U radu se razmatra izloženost čovjeka elektromagnetskim poljima od ekstremno niskih do mikrovalnih frekvencija. Ljudsko tijelo predstavljeno je realističnim računalnim modelima u smislu geometrije i električnih svojstava organa. Modeli na niskim frekvencijama temelje se na kvazistatičkim aproksimacijama, Laplaceovoj jednadžbi i numeričkome modeliranju primjenom metode rubnih elemenata. Modeli na visokim frekvencijama zasnovani su na cjelovitom elektromagnetskome modelu i odgovarajućoj Helmholtzovoj jednadžbi. U radu se razmatraju primjeri vezani za izloženost glave čovjeka elektrostatskom polju monitora, izloženost trudnice i fetusa poljima niskih frekvencija te izloženost oka mikrovalnim frekvencijama. Dobiveni rezultati upućuju na činjenicu da su pod nekim ekstremnim okolnostima mogući scenariji u okviru kojih karakteristični parametri polja prelaze granične vrijednosti propisane domaćom i međunarodnom legislativom. Primjerice, prilikom izloženosti trudne žene električnom polju dalekovoda, u fetusu se inducira višestruko veća gustoća struje od vrijednosti koja se inducira u mozgu trudnice. U radu su nadalje opisani mehanizmi interakcije elektromagnetskih polja s ljudskim tijelom. Nakon toga iznesene su dosadašnje spoznaje vezane za biološke učinke polja ekstremno niskih frekvencija i radio-frekvencija. Također su raspravljene zaštitne mjere vezane za međunarodne i domaće sigurnosne smjernice i granice izloženosti., This article describes a simulation method to assess human exposure to electromagnetic fields (EMF) from extremely low to microwave frequencies. Human body is represented by realistic computational models taking into account the geometry and electrical properties of organs. Low frequency models are based on quasistatic approximations, Laplace equation, and related numerical modelling via the boundary element method. High frequency models are based on the full wave model and the corresponding Helmholtz equation. The articles gives examples of computational models for the human head exposed to a video display unit, for a pregnant woman and foetus exposed to low frequency fields, and for the human eye exposed to microwave frequencies. In extreme scenarios, external and internal field levels exceed national and international tresholds. For example, pregnant woman exposure to power line electric fi eld causes several times higher values of current density in the foetus than the internal current density in the female brain. The article also discusses the interaction between EMF and human body and presents new fi ndings on biological effects of extremely low and high frequency EMF. It concludes with a discussion about protection measures required by international and national safety guidelines and exposure limits.

The operators of the single-axle tractors are especially exposed to hand-arm transmitted vibrations. These vibrations can cause the complex of vascular, neurological and musculoskeletal disorders, collectively named hand-arm vibration syndrome. Among these, the most common disorder is vibration induced white finger (Raynaud's phenomenon). The vibration levels were measured in three tractor's working conditions, namely idling, transportation and soil tillage. The vibration level on the handles was measured and analysed and frequency spectra for the chosen working conditions were obtained. The frequency-weighted acceleration, given in m/s^2, was calculated and obtained values are graphically presented. The measured vibration levels are then discussed with regard to the operator's daily exposure limits recommended by the ISO 5349. The vibration levels were much higher in the x and y directions than the z-direction in all working conditions. The vibration total values in idling, transportation and soil tillage were 3.37, 8.37 and 9.62 m/s^2, respectively. Results showed that the 10% of workers are exposed to a risk of vibration-induced white finger disorder of the hands after relatively short periods (3-4 years), if the tractor is used 8 hours per day in soil tillage and transportation at full load. Considering the criteria of the ISO 5349, the daily working time with single-axle tractor should be limited in order to protect the operator and work schedules should be arranged to include vibration-free periods.

The paper reports and analyses the results of vibration measurement carried out on a framesaw. Vibrations were measured on both the left and the right handle as well as on the operators seat acording to ISO 8662-8. The measured levels of the weighted accelerations of the vibration were compared to the daily exposure limits according to ISO 5349-1 and ISO 2631-1. Daily exposures were determined according to the same standards. There are more than forty framesaws at the moment in use in Croatia in use in Croatia and many framesaw operators have serious hands and spine problems. The complex measurements were carried out in order to find out the vibration level at the operators working area. The paper reports the measurement results of the vibration transmitted to the framesaw operator during an ordinary working day. Vibration was measured at all operations performd during the normal framesaw working cycle. The weighted r.m.s. acceleration was also calculated and the duration of the each single framesaw operation was measured. The energy-equivalent vibration level corresponding to the total duration of exposure was calculated, too. The measurement results showed that the framesaw operator, under the given measuring conditions, is exposed to a vibration level higher than recomended daily exposure limits. Also, the energy-equivalent vibration level is higher than the recommended limits.

The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs and marmoset monkeys to sarin vapour in air, the lowest-observable-adverse-effect level (LOAEL) of sarin for miosis. This is the concentration × time (C·t) value (t = 5 h) of exposure at which miosis becomes significant. The ratio of pupil and iris diameters, measured on digital photographs taken on-line during exposure, was calculated as a measure for miosis. The exposure concentrations were in the range 7-150 μg m-3 and the exposure times needed to achieve significant miosis were in the range 10-300 min. Both vehicle- and pyridostigmine-pretreated animals were used in the experiments. The latter pretreatment resulted in ca. 30% inhibition of erythrocyte acetylcholinesterase in both species. In vehicle-pretreated guinea pigs and marmosets the pupil size was decreased significantly (P < 0.05) at sarin doses of 1.8 ± 0.3 and 2.5 ± 0.8 mg min m-3, respectively. In pyridostigmine-pretreated guinea pigs and marmosets the pupil size was affected significantly (P < 0.05) at 1.8 ± 0.5 and 3.0 ± 0.8 mg min m-3, respectively. Evidently there is no significant influence of pyridostigmine pretreatment on the LOAEL. These data were addressed in light of the recommended occupational and detection limits for sarin vapour in air. It was concluded that miosis will occur during low-level sarin exposure at levels that are not detectable by the currently fielded alarm systems, assuming that humans are as sensitive for sarin vapour in air as guinea pigs and marmosets. Copyright © 2004 John Wiley & Sons, Ltd.

The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs and marmoset monkeys to sarin vapour in air, the lowest-observable-adverse-effect level (LOAEL) of sarin for miosis. This is the concentration × time (C·t) value (t = 5 h) of exposure at which miosis becomes significant. The ratio of pupil and iris diameters, measured on digital photographs taken on-line during exposure, was calculated as a measure for miosis. The exposure concentrations were in the range 7-150 μg m-3 and the exposure times needed to achieve significant miosis were in the range 10-300 min. Both vehicle- and pyridostigmine-pretreated animals were used in the experiments. The latter pretreatment resulted in ca. 30% inhibition of erythrocyte acetylcholinesterase in both species. In vehicle-pretreated guinea pigs and marmosets the pupil size was decreased significantly (P < 0.05) at sarin doses of 1.8 ± 0.3 and 2.5 ± 0.8 mg min m-3, respectively. In pyridostigmine-pretreated guinea pigs and marmosets the pupil size was affected significantly (P < 0.05) at 1.8 ± 0.5 and 3.0 ± 0.8 mg min m-3, respectively. Evidently there is no significant influence of pyridostigmine pretreatment on the LOAEL. These data were addressed in light of the recommended occupational and detection limits for sarin vapour in air. It was concluded that miosis will occur during low-level sarin exposure at levels that are not detectable by the currently fielded alarm systems, assuming that humans are as sensitive for sarin vapour in air as guinea pigs and marmosets. Copyright © 2004 John Wiley & Sons, Ltd.

The main purpose of this pilot study was to estimate the lowest observable adverse effect level (LOAEL) for the electroencephalogram (EEG) upon long-term, low-level exposure of vehicle-pretreated and pyridostigmine-pretreated marmoset monkeys to sarin vapour. This is the C·t value (t = 5 h) of exposure at which the EEG becomes significantly different from that resulting from air exposure of the same animals. The LOAELs for effects on the EEG in vehicle- and pyridostigmine-pretreated marmosets appeared to be 0.2 and 0.1 mg min m -3, respectively. Comparatively, the latter LOAEL values are at least an order of magnitude lower than the previously established LOAEL for miosis and only 2-5 times higher than the lowest observable effect level (LOEL) of bound sarin in blood. The second aim of the study was to analyse the EEG of the same marmosets again during a 5-h exposure to air 1 year after exposure to sarin vapour. All the marmosets still demonstrated significant (P < 0.05) EEG differences. In most vehicle-pretreated marmosets the energy (μV2) per EEG band was higher than that observed 1 year earlier, which might indicate that neurons had become more sensitive to excitation. This phenomenon was less pronounced in pyridostigmine-pretreated animals. Visual examination of the EEG records revealed clear bursts of alpha frequencies (ca. 9 Hz), resembling sleep-spindles, that were present more frequently in both groups of exposed marmosets than in naive animals. These late changes in spindle oscillation might be the result of changes in the cholinergic system due to exposure to sarin vapour 1 year previously. In conclusion, EEG abnormalities persisting for more than 1 year may occur in humans during long-term (5 h) exposure to subclinical levels of sarin that are not detectable by the currently fielded alarm systems. Copyright © 2004 John Wiley & Sons, Ltd.

The main purpose of this pilot study was to estimate the lowest observable adverse effect level (LOAEL) for the electroencephalogram (EEG) upon long-term, low-level exposure of vehicle-pretreated and pyridostigmine-pretreated marmoset monkeys to sarin vapour. This is the C·t value (t = 5 h) of exposure at which the EEG becomes significantly different from that resulting from air exposure of the same animals. The LOAELs for effects on the EEG in vehicle- and pyridostigmine-pretreated marmosets appeared to be 0.2 and 0.1 mg min m -3, respectively. Comparatively, the latter LOAEL values are at least an order of magnitude lower than the previously established LOAEL for miosis and only 2-5 times higher than the lowest observable effect level (LOEL) of bound sarin in blood. The second aim of the study was to analyse the EEG of the same marmosets again during a 5-h exposure to air 1 year after exposure to sarin vapour. All the marmosets still demonstrated significant (P < 0.05) EEG differences. In most vehicle-pretreated marmosets the energy (μV2) per EEG band was higher than that observed 1 year earlier, which might indicate that neurons had become more sensitive to excitation. This phenomenon was less pronounced in pyridostigmine-pretreated animals. Visual examination of the EEG records revealed clear bursts of alpha frequencies (ca. 9 Hz), resembling sleep-spindles, that were present more frequently in both groups of exposed marmosets than in naive animals. These late changes in spindle oscillation might be the result of changes in the cholinergic system due to exposure to sarin vapour 1 year previously. In conclusion, EEG abnormalities persisting for more than 1 year may occur in humans during long-term (5 h) exposure to subclinical levels of sarin that are not detectable by the currently fielded alarm systems. Copyright © 2004 John Wiley & Sons, Ltd.

Objectives: To revise the criteria used in the present 'Required Sweat Rate' standard ISO 7933 (1989) for the prediction of the maximum duration of work in hot environments. Methods: Review of the literature and in particular, of the bases for the present criteria. Results: A new method is proposed, to take into account the increase in core temperature associated with activity in neutral environments. The prediction of maximum wetness and maximum sweat rates are revised, as well as the limits for maximum water loss and core temperature. Conclusions: An improved set of maximum values and limits is described, to be used in the revised version of the ISO 7933 standard. Due to the major modifications to the 'Required Sweat Rate' index and in order to avoid any confusion, it is suggested that the revised model be renamed the 'Predicted Heat Strain' (PHS) model.

Objectives: To revise the criteria used in the present 'Required Sweat Rate' standard ISO 7933 (1989) for the prediction of the maximum duration of work in hot environments. Methods: Review of the literature and in particular, of the bases for the present criteria. Results: A new method is proposed, to take into account the increase in core temperature associated with activity in neutral environments. The prediction of maximum wetness and maximum sweat rates are revised, as well as the limits for maximum water loss and core temperature. Conclusions: An improved set of maximum values and limits is described, to be used in the revised version of the ISO 7933 standard. Due to the major modifications to the 'Required Sweat Rate' index and in order to avoid any confusion, it is suggested that the revised model be renamed the 'Predicted Heat Strain' (PHS) model.

We report a numerical study of the induced electric fields and specific absorption rate (SAR) produced by microwave radiation from a half-wavelength dipole near tissue models, and the resulting transient and steady-state temperature rises. Several models were explored, including a uniform emi-infinite plane of tissue, uniform sphere, a phantom model of the head filled with tissue-equivalent material, a numerical model of the head with uniform dielectric properties (obtained from a digitized computed tomography image), and a numerical model of the head with different dielectric properties corresponding to various tissues. The electromagnetic calculations were performed for half-wave dipoles radiating at 900 and 1900 MHz at various distances from the model, using the finite-difference-time-domain (FDTD) method. The resulting temperature rises were estimated by finite element solution of the bioheat equation. The calculated SAR values agree well with an empirical correlation due to Kuster. If the limiting hazard of such exposures is associated with excessive temperature increase, present exposure limits are very conservative and guidelines that are easier to implement might provide adequate protection.

The complex of vascular, neurologic, and osteoarticular disorders occurring in the upper limbs of vibration-exposed workers is called hand-arm vibration syndrome. There is epidemiologic evidence for an increased occurrence of peripheral sensorineural disorders in occupational groups working with vibrating tools. An excess risk for wrist osteoarthrosis and for elbow arthrosis and osteophytosis has been reported in workers exposed to shocks and low-frequency vibration of high magnitude from percussive tools. However, there are too few epidemiology data to enable reliable conclusions to be drawn about exposure-response relationships for both sensorineural disturbances and bone and joint disorders caused by hand-transmitted vibration. Cross-sectional and longitudinal epidemiology studies have shown that occupational exposure to hand-transmitted vibration from a great variety of hand-held tools is significantly associated with an increased occurrence of digital vasospastic disorders called vibration-induced white finger (VWF). The proposal of an exposure-response relationship for VWF has been included in an annex to the international standard ISO 5349. The findings of several epidemiology studies have shown a poor agreement between the risk for VWF observed in various occupational groups and that predicted by the ISO 5349 model. Both overestimation and underestimation of the occurrence of VWF have been reported by investigators. It has been argued that the current ISO frequency-weighting curve for hand-transmitted vibration may be inappropriate for the assessment of vibration-induced adverse vascular effects. Alternative exposure-response relationships for VWF have been suggested in recent epidemiology studies. The epidemiology data used to construct current exposure-response relationships for vibration-induced injuries are primarily derived from cross-sectional studies. Future epidemiology research should be based on prospective cohort studies because the design characteristics of such studies permit the study of cause-effect relationships and the formulation of etiologic hypotheses.

Background The toxicity of styrene on the peripheral nervous system is still debated. Cases The paper presents two cases of peripheral sensorimotor neuropathy in styrene-exposed workers. Exposure, evaluated by biological monitoring, ranged between 100 and 150% of the current limits proposed by the American Conference of Governmental Industrial Hygienists (ACGIH). The subjects complained of leg weakness and numbness, cramps, and paresthesia. Electrophysiology revealed a moderate peripheral sensorimotor neuropathy of a demyelinating type. Color-vision testing showed a subclinical deficit. Common inherited and acquired causes of peripheral neuropathy and dyschromatopsia other than styrene were ruled out by personal history, medical examination, laboratory data, and chest X-ray. Conclusion The results suggest that long-term occupational exposure to environmental levels of styrene that are equal, or slightly above, the ACGIH limits can induce a clinical form of peripheral neuropathy and a subclinical impairment of color vision. As a consequence, a careful reappraisal of the real preventive meaning of the current ACGIH occupational limit for styrene, at least on an individual basis, is needed.